One-Day DIY Roush Install - Bolt-On Mods, Part 5

We bolt a few additional goodies onto our Roushcharged 5.0 and head toward the 9-second slot.

Heading Back to the Dyno

We had a few more goodies to test out along with the new exhaust. With the factory wheels and tires at 38 psi, a Third gear pull was made (all previous runs have been done in this manner). The Pony came alive with the newfound power.

The exhaust-only horsepower gains were very impressive at a total of 38 rwhp and 16 lb-ft of torque without needing any adjustments to the tune. That equated to a stout 617 rwhp and 528 lb-ft of torque at the tires, simply by upgrading the exhaust and losing the cats.

We are still running the Shell URT Advanced race fuel, but soon will be forced to switch when our stash runs out since it’s no longer being made. There are some interesting fuel options hitting the market, so we will be testing to find the best fit for our application.

We did a quick on-dyno swap of the stock blower inlet elbow to a VMP Tuning ported elbow, and exchanged the Roush-supplied, twin-60mm throttle body to a single-blade FRPP Cobra Jet unit (PN M-9926-SCJ) in hopes that we would see an increase in overall boost. Jon Lund was working his remote tuning magic from New Jersey, while we were on the dyno in Baton Rouge. Technology is wonderful. At Lund’s suggestion, we also traded the Roush cold-air for a JLT cold-air intake (PN CAIBA-FMG-11).

After a couple of pulls, we were deflated, as the results did not meet our expectations. We expected to see much better gains from the ported elbow and massive throttle body. Perhaps it was the low boost level, but it only showed an increase of 1 measly horsepower.

We are hoping to see these parts work in conjunction with higher boost levels as we turn up the wick on our boosted build over the winter. We also saw no horsepower gain from the JLT cold-air. Don’t let this detour you from choosing this kit—the quality is excellent and it’s likely to show gains as we crank up our Coyote. Furthermore, Lund is confident the JLT cold-air’s gains will be better seen in a track environment and we were planning a track outing to put these parts to the test where it counts—on the track.

At this point, we were as desperate as the Kardashians. Since we had not seen the gains we expected, we needed more power before we called it a day. The only way to achieve that was to go to the smallest pulley available for our Roush TVS blower—a 69mm piece. After an easy swap, we were in business. The alabaster Steed turned the rollers once more and laid down a potent 661 rwhp and 573 lb-ft of torque with a peak boost level of 13.3 psi. In short, we gained a total of 80 rwhp at the tires with a simple exhaust and pulley swap with a custom tune. Always remember, it’s the sum of a good combination that will make your Pony run. And the more finely tuned a cars is in stock form, the more careful you must be when choosing your mods.

Back To the 1,320

There is nothing worse than a story that boasts big power numbers with no track numbers. It’s like watching a movie part-way and never knowing the ending—we just can’t leave you hanging like that. Of course we can’t get every car we do an install on to the track, but we sure try. While the Internet jockeys boast about dyno numbers, real enthusiasts ask: What did it run? And MM&FF does our best to give you those answers.

More importantly, we try to maximize our e.t. for the given power level. Not just make an abundance of power and hope it runs. On that note, this beast may not make massive numbers on the dyno, but it uses every last ounce of power extremely efficiently. Even being 3,900 pounds and with stock suspension, sway bars still intact, it launches with a vengeance. In fact, we love out-running high-rwhp dyno kings on the strip.

We also switched from the 325/50 Mickey Thompson drag radials to the smaller X275 Pro Radials, and it made a significant difference traction-wise. On a good track, the smaller, lighter tires will make the GT quicker (less rotating mass), but we run the risk of losing consistency on so-so track or on the street.

Now, with the new MBRP exhaust sounding wicked, we hit the local track for a quick test session. In similar weather conditions as previous test sessions (2,500-plus DA in serious Louisiana humidity), we ran a personal best of 10.22 at 136 with an insane, wheels-up 1.38 60-foot! Yes, you read it correctly—100-percent factory suspension.

We credit the custom BTS/Precision Industries for the hard launch improvement, especially since results like this are mostly only seen from high-horsepower setups that have aftermarket suspensions. We are just floored by how much engineering has gone into these new Mustangs. It truly is a new era of modern muscle. But wait, there’s more.

For us, the NMRA World Finals in Bowling Green, Kentucky, is the best all-Ford race of the year, and we were banking on the typical cool weather and low DA conditions to put our GT in the 9s. Unfortunately, it wasn’t in the cards.

Instead of a nice chill, we were racing in humid 90-degree air. Nothing like Mother nature to spoil the fun. But even so, our super-fresh five-oh still set a personal best of 10.19 at 135 (with a 1.42 60-foot) and that made us happy.

A couple of weeks later, we finally had the mine-shaft air at a track local to our home. We headed to Twin Cities Motorsports Park (Monroe, Louisiana). With a density altitude of minus 400 feet, the 9s were so close we could taste them. I staged shallow and stalled the howling Coyote to 2,000 rpm and it launched with a vengeance. The GT powered out of the hole and ripped to a 10.02 at 141 mph. Close, but not there.

After a short cooldown, I headed back and repeated, this time it recored a sick 1.31 60-foot time and blasted into the 9s with a 9.86/138 mph pass! What’s most amazing is that the suspension is 100-percent stock, right down to the factory anti-roll bars.

Now that we’ve gone 9s, it’s time to find a new goal for the GT. So chime in on the MM&FF Facebook fan page and drop your comments and suggestions on what we should do next.